a. Field of the Invention
The present invention relates to x-ray based imaging systems. More particularly, the present invention relates to a reduced radiation fluoroscopic imaging system in which a three-dimensional model of an internal anatomic structure of a patient is integrated and registered with a two-dimensional fluoroscopic image generated by a fluoroscope.
b. Background Art
It is known that a wide variety of imaging systems can be used to assist a clinician/physician in the performance of various catheter-based diagnostic and therapeutic procedures relating to different parts of the human anatomy, such as, for example, the heart. One conventional imaging method is fluoroscopy. In fluoroscopy, a fluoroscope is used to provide clinicians/physicians with real-time two-dimensional images of internal anatomic structures of a patient. The fluoroscope further provides a means for monitoring the location and position of medical instruments, such as catheters, that are disposed within the patient at locations within the field of view of the fluoroscope during the performance of a particular procedure.
In general terms, a fluoroscope consists of a radiation source (i.e., x-ray source) and a fluorescent screen. In practice, a patient is placed between the radiation source and the screen, and x-rays are directed toward the particular region of the patient's body that is within the field of view of the fluoroscope and that a clinician/physician wishes to image. As the x-rays pass through or are absorbed by the patient, images are created on the fluorescent screen. The fluoroscope may also include a monitor electrically connected to the screen upon which the images may be displayed. One drawback of fluoroscopy, however, is that it provides relatively poor anatomic detail due, at least in part, to the two-dimensional images that it creates. Additionally, to provide useful images, the patient and/or the clinician/physician performing the procedure or operating the fluoroscope may be exposed to relatively high doses of radiation, which is considered to be undesirable for both the patient and/or the clinician/physician.
Other conventional imaging methods include computed tomography (CT) and magnetic resonance (MR) imaging. In these methods, a patient is scanned in a CT or MR imaging instrument in order to acquire image data relating to particular internal anatomic structures of the patient. Using various techniques and software, the acquired image data can be processed and a three-dimensional model of desired anatomic structures can be generated. While these methods are useful in obtaining high quality and detailed images of particular internal structures of a patient, they also are not without their drawbacks. For instance, by themselves, these methods cannot assist a physician in catheter-based procedures being performed on a patient since they do not allow sufficient visualization for the navigation and guidance of certain types of catheters. More particularly, these systems do not readily provide real-time images that can be used to monitor the location and movement of the catheter relative to the internal structures of the patient's body.
As a result of the aforementioned drawbacks of conventional imaging systems, technology has been developed that combines the advantages of each of the above described imaging methodologies. Such technology includes integrating and registering the three-dimensional model created by the CT or MR methods, with the continuous real-time generation of two-dimensional images by the fluoroscope. By combining the respective methodologies, a clinician/physician is able to view detailed three-dimensional anatomic models superimposed on the real-time two-dimensional image in order to enhance the anatomic detail, while at the same time, monitoring the location and movement of the catheters or other instruments using the two-dimensional real-time fluoroscope image as he/she moves catheters within the patient. Accordingly, this technology adds improved anatomic visualization to conventional two-dimensional imaging systems, and catheter visualization and guidance to the three-dimensional modeling systems.
However, as with the methodologies described above, the current state of this particular technology has its disadvantages. For instance, as described above with respect to conventional fluoroscopic techniques, since fluoroscopy is required to visualize catheter location and movement, the patient and/or the clinician/physician are exposed undesirable amounts of radiation to adequately or sufficiently image the catheters in the patient. Another disadvantage or deficiency is that the current technology does not allow for mapping of the modeled anatomic structure. In other words, physiological and/or electrophysiological data relating to the modeled anatomic structure that is acquired by the catheter cannot be superimposed or otherwise displayed or visualized on the three-dimensional image.
Accordingly, there is a need for an imaging system that will minimize and/or eliminate one or more of the above-identified deficiencies.